Filament guide



5 "M. H. BARNES ETAL FILAHENT GUIDE Filed lay 2;, 1944 lNVENTOR MALCOLM H.BARN11S' Eomw L. mcmoLzss ATTORNIY Patented Oct. 25, 1949 UNITED STATES PATENT 'OFFi lZt FILAMENT GUIDE Malcolm n. Barnes and Edward L. meanness, Kenmore, N. Y., asslgnors to The Linde Air Products Company, a corporation of Ohio Application May 23, 1944, Serial No. 586,964 I I r 11 Claims. 1

The principal object of this invention is the provision of novel filament guides having improved resistance to the wearing and cutting action of rapidly moving filaments such as thread, yarn, wire, and ribbon. Another object is the provision of a novel filament guide having such a long life that a relatively high initial cost will be more than offset by the relatively low cost per yard of filament passing over the guide, hereinafter called the unit cost.

Large textile mills require thousands of thread guides to guide and support the threadduring its passage from one operation to another. Thread guides constructed in accordance with the prior art wear out quite rapidly and require frequent replacement, especially when the thread is impregnated with an abrasive material, such as titania, as is often done with rayon and other synthetic fibers. Among the many materials which have been used for thread guides in the prior art are cobalt-chromium-tungsten alloy, borosilicate glass, porcelain, soft glass, stainless steel, nickel-chromium wire, and sintered alumina, but none of these materials has given completely satisfactory results. The principal objections to these materials are their relatively low resistance to the wearing and cutting action of rapidly moving thread, and their relatively high unit cost. Furthermore, a worn or cut thread guide, which is often detected too late, may damage many yard of thread before replacement is made. Similar undesirable conditions have long existed in industries manufacturing and using metal wire.

The present invention will be readily understood from the following detailed description having reference to the accompanying drawing,

wherein:

Figs. 1 and 2 are enlarged side and end elevational views, respectively, of a pigtall type of filament guide;

, Figs. 3 and 4 are elevational views of two other types of filament guides, Fig. 4 being greatly enlarged.

Figs. 5 and 6 are enlarged side elevational views of two other types of filament guides, used as thread tensioning devices; and

Fig. "l is a greatly magnified longitudinal sectional view of a fragment of one type of filament guide.

In the following description the term filament guide is used to denote any type of device for guiding and supporting filaments such as textile threads, metal wire, and yarns, as well as ribbon-like filaments, regardless of whether the device is used solely as a guide or has secondary functions, such as stretching or tensioning the filament. Furthermore, although several specific types of filament guides are described in detail, this is by way of illustration only. The principles of the invention are applicable to filament guides in general, regardless of shape or construction. A few examples of filament guides are simple guides, tensioning posts,- the orifice guides of steam stretching chambers, and the eyes of needles and shuttles.

We have foundthat a filament guide having at least a filament contacting portion comprising a unicrystalline body of material selected from the group consisting of corundum and spinel, either natural or synthetic, is far superior to the fllamentg'uides of the prior art in its resistance to wearing and cutting, as well a in its low unit cost. Corundum, of course, is substantially pure alumina, best known as natural or synthetic crystalline rubies and sapphires; and the spinel used is a magnesia-alumina crystal which may contain between 8% and 28% of magnesia, the balance being substantially all alumina. Synthetic corundum and spinel single crystals are made either as large boules or as thin long rods by the method, or variations thereof, fundamentally disclosed in Verneuil Patent 1,004,505, by dropping alumina or alumina-magnesia powder through a gas flame, and accumulating and solidifying the fused materialon a suitable support.

The filament guides of the invention are particularly advantageous when they have glossy, scratch-free filament contacting surfaces substantially identical with the surface produced by intensely heating a rough surface layer of a spinel or corundum body until the desired finish is obtained. It is thought that the rough surface portions fuse and coalesce in the heat to form the desired glossy, continuous, smooth,'and scratch-free surface. However, it is possible that the surface is heat glossed by a solid diffusion mechanism. Heating may be accomplished by a gas flame, in a furnace, or in any other desired manner.

Another method for heat glossing a spinel or corundum filament guide is to apply to a rough surface a thin film of an addition agent, such as an oxide or oxide-forming compound, fulfilling at least one of the following requirements: having a lower melting point than the guide material, forming a eutectic with the guide material, forming a solid solution with the guide material, and forming a low melting perltectic with the guide material. The film is then bonded to the original surface by heating the body intensely in any suitable way. Here also it is not known for certain whether the glossing action a,4as,sss

proceeds by melting the material, or by a solid um oxide, and silica.

Heat glossed surfaces resist wear and cutting by filaments such as thread, yarn, and wire much better than do unglossed surfaces or abrasively polished surfaces. The small crevices in unglossed surfaces and the minute scratches always existing on abrasively polished surfaces act as concentration points for the wearing and cutting action of the filament as it passes over the thread guide.

It is especially desirable to form our novel filament guides from long, thin, homogeneous rods of material selected from the group consisting of corundum and spinel, because of the adaptability of such rods for this type of device. Such rods, usually having a diameter of three sixteenth inch or smaller as grown by a variation of the fundamental Verneuil process, can be used in the straight condition in the manner shown in Fig. 6 of the drawing. They are most advantageous for filament guides, however, when they are formed into shapes especially designed for guiding filaments. For example, a rod of corundum or spinel can be bent to form a filament guiding bight or loop simply by heating a portion of the rod in a flame to its softening point, and then applying force transversely of the longitudinal axis of the rod. It is advantageous, to reduce friction and wear, that such guides be polished either with abrasives or by heat glossing, preferably the latter which increases resistance of the guides to wearin and cutting by the filament. Heat glossing generally occurs spontaneously over that portion of the rod which is heated for forming it into a special shape,

Figs. 1 and 2 show details of a mounted pigtail type filament guide comprising a horizontally mounted homogeneous rod ll of corundum which the roughly ground surfacesforming the notch 2| are heat glossed for greater resistance 7 to wearing and cutting by the filament.

The guide shown in Fig. 5 is a tensioning device comprising a rod 35 of corundum or spinel having a neck portion 31 of reduced cross-sectional area, which has been formed by heating the central portion of the rod to plasticity and then stretching the rod. Due to the heat, the neck 31 has a heat glossed surface free from scratches. The rod 35 is mounted adjacent to .its ends in two sleeves 39 and H, and the filaor spinel bent through 360 into the form of a bight l2, and mounted in a supporting sleeve i3 in position for the passage of a filament I5 through the bight.

-Fig. 3 shows a different form of filament guide i'l consisting of a homogeneous corundum or spinel rod bent through 180 to form a J-shaped bight l8, which may be mounted in any suitable manner to guide a filament through the bight. It is evident thatrods having bights of different shapes than those shown in Figs. 1 to 8, such as closed bights and eyes, are useful as filament guides.

Fig. 4 shows a disc shaped filament guide I 9 of corundum or spinel having a V-notch 2i. Such a guide is usually shaped from a large piece of corundum or spinel by cutting and grinding, after ment 42 is wound one or more times around the neck 31 to maintain a desired tension on the filament during its passage, while preventing the filagient from wandering along the length of the an e.

In Fig. 6 the guide or tensioning device forguiding a filament 49 is a straight homogeneous rod 43 of corundum or spinel mounted similarly to the rod of Fig. 5 in sleeves 45 and I! adjacent to the ends of the device. It is desirable to have a heat glossed scratch-free surface on the rod 43, but the unpolished rod in the condition "as grown also has far superior resistance to wear than the materials used for filament guides in the prior art. Moreover, the straight rod shown in Fig. 6 can be provided with either a smooth fully glossed surface, or with a partially glossed wavy scratch-free surface having smooth undulations, as shown on a greatly magnified scale at 5| on the fragment of a rod 53 in Fig. '7. Such a wavy surface can be produced by heating the surface of the as grown rod until the many small crystal projections on the rod are rounded oil, and then discontinuing heating before the attainment of an even, completely glossed surface. Another procedure -for forming a wavy surface is to overheat the rod. A wavy surface is of particular value for straight guides and tensioning devices, and in the trade the wavy surface is sometimes spoken of as giving less friction.-

The following table shows the results of accelerating abrasion tests carried out on spinel and corundum rod filament guides, in comparison with rod filament guides of other materials. In

across each guide. The figures in the table are.

approximate but sufiiciently accurate to provide a fair comparison among the several thread guides.

A prox. First D in. of I Evidence. Guide Material Guide, Finish Out- Y/D inches ing, Yards 1)... Synthetic sapphire 0. 10 Heat glossed. 234, 000 2) d0 0. 14 d0-. 179,000 3).-- 0.23 do 152,000 4) 1 0.28 Diamond polished (400 mesh) 25, 050 90, 000 (5). 0. 16 I Heat glossed 700 111,000 26) o 0; 29 Diamond polished (600 mesh) 25, 050 87, 000 7g Sintered Aluinma 0. 25 60, 000 (8 o 0. 24 42, 000 (9) Co-Oi -W alio 39,000 Bor'osilicate g ass 22, 000 Soft glass.. 0 20, 000 Porcelain 12, 000 Stainless Steel (18 Cr, 8 Ni) 18,000

Nickel-Chromium wire 27, 000

It is apparent that the spinel and the sapphire (corundum) filament guides were far superior to the other guides tested, especially when the factor of size variation is eliminated. This superiority is emphasized and rationalized as in the column headed Y/D, by dividing by the guide diameter the number of yards of thread passed over the guide before the first evidence of cutting was observed.

-Several types of filament guides have been described specifically above to illustrate the principles of the invention. It is to be understood that the invention is not limited to such specific types but that changes in construction and arrangement can be made within the scope of the appended claims.

We claim:

1. A filament guide comprising a unicrystalline body of material selected from the group consisting of corundum and spinel, said body having a glossy scratch-free filament contacting surface substantially identical with the surface produced by intensely heating such a body.

2. A filament guide according to claim 1, wherein said body is corundum.

3. A filament guide according to claim 1, wherein said body is magnesia-alumina spinel.

4. A filament guide according to claim 1, wherein said body is a. long thin rod.

5. A filament guide comprising a unicrystalline rod of material selected from the group consisting of corundum and spinel, said rod having a bight for the passage of a filament, said bight having a glossy scratch-free filament-contacting surface substantially identical with the surface produced by intensely heating a surface layer of such rod.

6. A filament guide comprising a straight unicrystalline rod composed of material selected from the group consisting of corundum and spinel, said rod having a glossy scratch-free filament-contacting surface substantially identical with the surface produced by intensely heating a surface layer of such a rod.

7. A filament guide comprising a unicrystalline rod composed of material selected from the group consisting of corundum and spinel, said rod having a filament-contacting neck section of gradually reduced cross-sectional area, said neck section having a. glossy, scratch-free surface substantlally identical with the, surface produced by intensely heating a surface layer of such a rod.

8. A filament guide having at least a filamentcontacting portion comprising a unicrystalline body of material selected from the group consisting of corundum and spinel, said body having a glossy scratch-free surface produced by heat bonding to the original body at least one oxide fulfilling at least one of the following requirements: having a melting point lower than such material, forming a eutectic with such material, forming a solid solution with such material, and forming a low melting peritectic with such material.

9. A filament guide having at least a filamentcontacting portion comprising a unicrystalline 'body of material selected from the group consisting of corundum and spinel, said body having a glossy flame-polished surface.

10. A filament guide comprising a unicrystalline rod of material selected from the group consisting of corundum and spinel, said rod having a bight bent therein for the passage of a filament, said rod having a glossy scratch-free surface substantially identical with the surface produced by intensely heating such a rod.

' tacting surface, said surface being substantially identical with the surface produced by intensely heating such a rod.

MALCOLM H. BARNES. EDWARD L. McCANDLESS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA'IENTS Number Name Date Re. 12,769 Palmer Mar. 24, 1908 110,535 Altemus Dec. 27, 1870 181,394 Bancroft Aug. 22, 1876 423,847 White Mar. 18, 1890 1,967,798 Witte July 24, 1934 2,060,964 Wider Nov. 17, 1936 2,214,703 Thurnauer Sept. 10. 1940 

